Alkyl sulfoxide compounds for insect combating and method



states r ALKYL SULFOXIDE COMPOUNDS FOR INSECT COMBATING AND METHOD LyleD. Goodhue, Roy E. Stansbury, and Rector P.

Louthan, Bartlesville, Oklal, assignors to Phillips Petroleum Company, acorporation of Delaware No Drawing. Filed May-'27, 1957, Ser. No.661,584

37 Claims. (Cl. 167-22) This invention relates td' combating of insects.In one of its aspects, the invention provides certain selected alkylsulfoxides, as defined herein, as ingredients for insecticidalcompositions. In a further aspect, the invention provides one or more ofcertain selected alkyl sulfoxides as essential active ingredients ininsecticidal compositions. In another of its aspects, theinventionprovides certainselected alkyl sulfoxides, as defined herein, as atleast in part replacement materials for pyrethrum in insecticidal orinsect combating compositions. In another of its aspects, the inventionprovides a method for combating insects. In a specific form, theinvention provides the insecticidal sulfoxides, as defined herein;alsoas insect repellent agents. A further specific aspect is in the useof said repellent agents in insect combating compositions which may ormay not contain one of the other insecticidal sulfoxides of the presentinvention. Insecticidal mixtures are Widely used to control flies,

roaches and other insects. The field of insecticides is H dividedbroadly into two classifications, agricultural insecticides andhousehold insecticides. While the primary purpose of both of these typesof' insecticides is to kill the insect, other properties are alsodesirable, particularly, in the household variety of insecticide whichis, of course,- used within a confined space, or indoors. For example,

the housewife is particularly-interested iii obtaining aninsecticidewhich will quickly cause knockdown (pa= ralysis) of flies, etc., eventhough the insect being attacked does not die for some period of time.The most widely used agent in insecticides which causes knockdown offlies and the like is pyrethrum. However, pyrethrum is extremelyexpensive, and even though very small amounts ofpyrethrum are employed,it is advantageous, from an economic standpoint, to reduce the amount ofpyrethrums in a given'insecticidal mixture if this can be done withoutdecreasing the rate of knockdown. Numerous agents have been found whichcan be employed in conjectidn with pyrethrum which cause fasterknockdown than either the agent or pyrethrum alone. These agents,commonly referred to as pyrethrum synergists, are doubly b'eneficial-in'that th'ey'e'n'able one to reduce the amount of pyrethrum necessarytdobtain quick knockdown. Also, repelling of certain insects isanimportant objective in agriculture, industry and in the household.

It is an object of this invention to provide insect comhating agents.Another object is to provide insecticides; Itis a further'object of thisinvention to provide additives for insecticides. It is another object ofthis invention'to provide a method for cornbating'insects. Anotherobject of the invention-is to provide insect repellents. It-is afurtlier object of this invention to-providea method for re- 2,957,799Patented Oct. 25, 1960 "ice 2. pelling insects. It is a still furtherobject of this invention to provide certain repellents for use in insectcombating compositions. A further object still is the provision of areplacement agent for pyrethrum.

Other aspects, objects and several advantages of the invention areapparent from a study of this disclosure and the appended claims.

It has now been discolvered that the selected sulfoxide compounds,defined herein, are effective insect combating agents, such asinsecticides and repellents, as well as additives for insect combatingcompositions, as more fully specified and described herein. 7

According to the invention, there is provided a method of combating aninsect which comprises applying to the place at which said insect may bepresent aneifective quantity of at least one compound having thefollowing structural characteristics wherein R is air n' alkyl radicalhaving 1-12 carbon atoms, R is a radical selected from the groupconsisting of nand secondary alkyl radicals having 18 carbon atoms andwherein the total carbon atoms in R and R are in the range 7-13,inclusively.-

Also, according to theinvention and as a more specific feature thereof,there has been provided a' method for combating insects byrepellin'g'the same, especially for repelling housefiies and roaches,which comprises applying to the place at or within the confined space inwhich said insect may be present an effective quantity of at least onecompound selected from the group consisting of the following sulfoxides:

Methyl n'-nonyl sec-Octyl ethyl (crude) n-Butyl n-heptyl n-Arnyl n-hexyl -Q y -P opy n-Decyl methyl n Nonyl ethyl di-n-Hexyl n-Butyln-octyl n-heptyl-n-amyl Methyl n-undecyl n-Decyl ethyl n-Dodecyl methyln-But'yl n-propyl Ethyl n-hexyl' di-n-Butyl n-Heptyl methyl n-Amyln-pro'pyl n-Amyl n-butyl n-Propyl n-hexyl Ethyl n-heptyl Methyl n-octyldi-n-Amyl I n-Butyl n-hexyln-Heptyl n-propyl Ethyl n-octyl Z-Ethylhexylethyl Compositions according to the invention can be made up in usualmanner according to prior art knowledge; However, a particularlyefiective composition is obtained employing deodorized kerosene. Anotherpresently less preferred composition is that obtained employing asubstantially odor-free Soltrol (a trademark) which is an isop'arafiinichydrocarbon solvent fraction boiling in the approximate range of 260Q F.and which preferably has been prepared by hydrofluoric acid alkylationwith an olefin under alkylation conditions known in the alkylation artas exemplified in US. Patent 2,773,920, issued December 11, l956, in thenames of L. H. Vautrain and E. Strunk. The deodorized kerosene is morepreferred because it is capable of imparting better effectiveness to'the overall composition; Deodorize'd kerosene consists primary ofaromatic and straight chain aliphatic hydrocarbons and the preferredsolvent boils in the range 300- 600 F. More preferably the solvent iskerosene which has been deodorized by a process such as steam strippingployed as agents for killing houseflies which, of course, are sought tobe killed in or repelled in or within a house or other confined space.

EXAMPLE I and boils in the range of about 385-500 F.

The compounds used in this invention are usually A number of compoundswere tested for insecticidal eflective when employed in a composition inan amount properties by the following procedure. within the rangebetween 0.25 and 15 percent by weight, An amount of the chemical to betested was dissolved based on the total composition. Proportionssomewhat in a suitable solvent, and a volume of the resultingsoluoutside of this range can also be employed, but are not tion wassprayed into the space confined within a Peetnow preferred. When usingthe compounds according to Grady chamber in which a known number ofhousefiies this invention in an insecticidal composition, it ispreferred were contained. The Peet-Grady chamber is a chamber to employan amount within the range between 1.0 and of 216 cubic feet capacity(6x6'x6'). The number of 10 weight percent. When the compounds of thisinvenflies knocked down, e.g., paralyzed or dead, was tion are employedas replacement for pyrethrum, it is counted at various time intervals,and the total number preferred to employ an amount within the range offrom of flies that were dead at the end of 24 hours was counted. 0.25 to5 weight percent based on the total composition. The results of thesetests are expressed below as Table I. In compositions co'ntaining bothpyrethrum and the in- In Table I, which follows, the runs employingdimethyl secticides of this invention, it is preferred to use a ratio ofsulfoxides, diethyl sulfoxide, tert-butyl ethyl sulfoxide, the compoundsused in this invention to the pyrethrum in di-n-octyl sulfoxide anddi-isopropyl sulfoxide are control the range of from 6:1 to 20:1 byweight. A more preruns, and represent sulfoxides which are not withinthe ferred ratio is in the range of from 8:1 to 10:1. When scope of thepresent invention and which, therefore, are using the compoundsaccording to this invention for repelnot within the scope of the generalformula given in this ling insects, the concentration in the solution inwhich the specification. All other runs employing a dialkyl sulfoxidecompounds are applied usually will be in the range 0.5 represent runswithin the scope of the invention. The two to 10 weight percent andpreferably will be 1 to 5 weight runs in which pyrethrums and the onerun in which percent. This is for application in the usual manners.lethane were employed are also control runs.

Table 1 Per- Amt. of Wt. per- Percent Flies Knocked Down" After centSolution cent Time in Minutes Flies Chemical Tested Sprayed, SolventUsed Chemi Dead cc. on] in After Solution 24 2 4 5 e s 10 15 Hrs.

10 Deodorized kerosene 16.0 94 99 100 91 10 do 12.1 94 100 100 44 12 .i.]do I. 1 8.68 52 a0 93 96 100 m (2 C O exanone 12 {10. ml deodorizedkerosene 39 70 89 95 96 53 12 Deodorized kerosene 10.1 74 94 95 95 96 8612 do 5.1 36 69 76 79 92 12 do 0.616 92 35 12 do 0. 6l6 93 97 9s 99 99.53 12 do.. 3.68 51 95 9s 97 9s 29 12 9.56 0 0 0 0 0 2 10 12.1 4 s s 6 1A etone {8 D eodorized kerosene- 18 22 34 18 12 {if-i:ii$%2$izt%f;a;aaa::::} M1 1 9 19 28 38 6 12 Deodorized kerosene 5.6 1117 23 26 24 5 1 Oflicial test insecticide (OTI) pyrethrum. 1Beta-butoxy-beta-thiocyanodiethyl ether.

The compounds used in the present invention can be applied or used inany of the forms in which insecticides are commonly used. For example,these insecticides can be employed in the form of solutions, emulsions,dusts, wettable powders, aerosols and the like. The preferred method ofapplication of these insecticides is in the form of aerosols,particularly, when the compounds of this invention are being employed aspyrethrum synergists in insecticidal compositions.

When applying the sulfoxides used in this invention, either alone or incombination with other ingredients, in the form of aerosols, they can bedissolved or dispersed in such solvents as naphthas, kerosenes, toluene,cyclohexanone, acetone and the like. These solutions can then beemployed in an aerosol bomb in conjunction with a compressible materialsuch as Freon and other similar preferably non-hazardous materials.

The insecticides of this invention are applicable for use in killingsuch insects as flies, ants, gnats, roaches and the like, although theyare particularly efiective when em- It will be noted from Table I thatdimethyl sulfoxide possesses no knockdown. When diethyl sulfoxide isused, the number of flies apparently knocked down is so slight as tomake diethyl sulfoxide Worthless as a knockdown agent. Furthermore, itwill be noted in Table II that dimethyl sulfoxide in combination withpyrethrum does not exhibit any synergistic action.

EXAMPLE H described in Example I. The results of these tests are out bythe same procedpre described in Example I. In the runs of the followingexample, the solvent employed was the deodorized kerosene sold under thetrade name of Apco 467, described above, unless otherwise indicatedexpressed below as Table II. by one or more asterisks.

Table III Actual Percent Knockdown Amt. Gms. in Mins. No. of 24-HourSulfoxides Employed Sprayed Chemical Buns Mortality,

(00.) Sprayed Avgd. percent 2 4 6 8 10 Di-n-hexyl 12 0. 36 42 57 76 8489 3 26 Do 12 O. 24 32 16 66 80 87 1 16 n-heptyl methyl. 12 0.36 65 8694" 95 98 2 12 Do 12 0.24 72 88 93 95 96 2 10 12 0.12 23 29 32 31 35 212 12 0.06 14 21 26' 31 36 1 13 n-amyl n-propyl- 12 0. 36 52 5O 59 63 711 10 n-amyl n-butyl- 12 0. 36 49 88 92 94 97 2 32 Do 12 0.24 39 58 74 7892 3 11 n-hexyl n-propyl-.. 12 0. 36 50 94 91 93 95 2 ,39 Do 12 0. 24 2739 57 82 86 3 3 ethyl n-heptyl. 12 0.36 75 94 96 97 98 2 30 Do 12 0.2447 71 76 93 '95 2 12 0. 36 85 97 98 99 99 3 33 12 0.24 71 90 95 96 97 326 12 0. 12 29 54 60 65 66 2 5 12 0. 06 16 31 34 40" 42 1 3 12 0.36- 4764 93 96 96 2 26 12 0.24 40 54 86 92 94 2 16 12 0.36 69 90 94 96 97 2 120.24 35 65 70 78 92 2 ll. 12 0.36 70 92 94 95 97 2 33 12 0. 24 57 83 8990 92 2 12 12 0.36 38 59 86 92 94 2 35 12 .0. 24 25 .37 ,46 54 71 1 .612 0.36 52 70 90 95 96 2 Not Determined. 12 0.24 28 4O 46 49 87 1 16 120. 36 60 90 95 97 98 2 29 12 0.24 55 65 89 92 94 2 21 1 12 0.36 25 4O 5181 86 1 28 '12 0.36 29 43 67 80 86 3 39 12 0.24 35 39 49 85 90 1 12 0.12 31 39 41 47 76 1 20 12 0. 36 52 66 74 80 77 1 38 12 0.36 50 84 92 942 34 12 0.36 31 43 p 50 59 89 1 35 12 0.36 28 35 61 86 92 1 47 methyln-nonyl- 12 0. 36 90 -95 98 99 I 100 2 41 Do 12 0.24 V 52 89 I 94 97 982 21 Do 12 0.12 36 79 84 87 89 2 8 n-nonyl ethyl 2 12 0.36 64 94 97 9899 2 41 Crude sec-octyl ethyl- 12 0. 36 64 85 91 94 2 16 Di-n-amyl 120.36 8O 92 96 97 2 26 Do 12 0. 24 36 48 59 68 90 2 1 9 Crude tertpctylmethyl 3 12 0.36 2 6 4 11 11 1 11 Di-n-heptyl 4 12 0.36 30 44 47 49 2 321 This run employed a solvent comprising a 40 percent (by vol.)solutionof Stoddard solvent in deodorized kerosene.

2 Solvent was 4 percent by 'vol. cyclohexanone in deodorized kerosene. 3Solvent was 10 percent isopropyl alcohol in deodorized kerosene. 4 Thisrun is an average of two runs, the first of which employed a solventcomprising 5 percent (by vol.)

cyclohexanone in deodorized kerosene.

in deodorized kerosene.

1 This solution was a solution which contained 0.03 percent by weightpyrethrum and 99.97 percent by weight deodorlzed kerosene.

Dimethyl sulfoxide, which precedes the Control in Table 11, represents anon-eifective sulfoxide which is not within the scope of the presentinvention.

EXAMPLE III A number of runs were made in which the insecticides ofExample I were tested for effectiveness as knockdown agents forhouseilies. The insecticides were tested at lower concentrations inthese runs than in Example I. The runs which are given below as TableIII were carried The second used a solvent comprising 2 vol. percentcyclohexanone In Table 111 there are included di-n-heptyland crudetert-octyl methyl sulfoxides which are not within the scope of theclaims to this invention.

EXAMPLE IVHOUSEFLY REPELLENCY A number of runs were made in which thesulfoxides of this invention were tested to determine their repellencyto houseflies. Repellency to houseflies was determined by the SandwichBait method which is essentially that disclosed by L. D. Kilgore inSoap, June 1949. In accordance with this method, to a sheet of cardboardwere applied two smooth, thin strips of unsulfured molasses about /swide and 3 /2" long leaving a margin of at least A" all around and aspace of at least 1" between the strips. The prepared cardboard stripswere then oven dried at 45 C. Strips of highly porous lens paper, 1 by4" in dimension, were impregnated with the sulfoxide to be tested as afly repellent by immersing them in an acetone solution containing thedesired quantity of the chemical, and then allowing the strips to dryover a period of 2 to 3 hours. An impregnated strip was thensuperimposed on each strip of molasses and was .fastened in place bystapling itin place to the cardboard ber of roaches on each treatedpaper.

Table IV Number of Flies Feeding at Indicated Time (Min) lfrun SulfoxideEmployed n-butyl n-octyl- 0 O 0 0 0 0 0 O 1 n-decyl ethyL. 0 0 0 0 1 O 1O 0 di-n-amyl 0 2 6 4 9 1 2 1 2 di-n-hexyl 0 1 2 2 1 8 0 0 0 n-amyln-butyL 0 1 1 1 7 9 14 3 2 n-propyl n-hexyL 1 0 3 12 3 9 6 1 4 methyln-octyl. 1 0 ll 14 8 9 6 6 6 n-buty] n-heXyL 0 0 0 0 1 1 7 2 8 n-heptyln-propyl. 0 0 0 1 3 1 10 2 2 ethyl n-octyl 0 0 0 2 0 0 5 4 2 1 0 l 3 2 01O 5 1 O 1 2 0 4 2 O 3 2 3 3 3 3 O O 1 l 6 3 5 6 5 4 5 5 3 4 3 1 1 2 1 02 0 3 methyl n-undecyl. 5 5 3 4 2 5 2 9 5 17---. methyl n-nonyl 0 0 0 02 1 3 2 6 l 0 0 0 1 0 0 0 l 4 50+ 50+ 33 24 50+ 21 gone 1 2 45 21 gone22..-- d1 1so-butyl. 2 18 gone 23 tert-butyl n-butyl 50+ gone 24.---di-n-heptyl 27 12 6 gone tert-octyl methyl 15 28 30 25 gone backing. Theloose fibrous construction of the impregnated lens paper permits theflies to remove the molasses through the paper. The prepared strips werethen exposed to about 150 houseflies, musca domestica, over 5 days old,which had been starved for 6 hours. The number of flies feeding on themolasses strips are recorded after 5 and 15 minutes, and each 15 minutesthereafter for 165 minutes. The results of these tests are tabulatedbelow as Table IV. In this table, the word gone is used to denote thecomplete consumption of the molasses. For comparison purposes, the flieswill completely consume the molasses in 15 to 30 minutes, and sometimesin as short a time as 5 minutes, when the material is non-repellent orwhen no repellent has been applied to the lens paper.

EXAMPLE VROACH REPELLENCY TESTS A number of runs were made in which someof the sulfoxides of the present invention were tested for repellency tothe American roach. In these runs, an apparatus was used which was madefrom three 4" by 4" glass cylinders with U-shaped openings to allow freepassage of the roaches to any of the cylinders. The three cylinders withopenings coinciding were taped together and placed on a piece of windowglass to form a bottom. Filter papers were slipped under each cylinder,and 5 roaches were introduced into the cylinders in the evening beforethe test was to start in the morning so as to give them a chance tobecome accustomed to new quarters. On the day prior to testing, 11centimeters diameter filter papers (Whatman No. were dipped in acetonesolutions containing 5 percent of the sulfoxide to be tested. At thebeginning of the test, the dried, chemically treated papers weresubstituted for the untreated papers under the outer two cylinders, anda clean untreated paper was placed under the center cylinder. After onehour, readings were taken on the number of roaches on each treated paperand the number on the untreated paper. The roaches were then stirredagain to force them to again choose the least objectionable paper. Thisreading and stirring process was done each hour until 6 hours hadelapsed from the beginning of the test. The following day, two readingswere taken, 6 hours apart. At the end of the test, the results wererecorded as the sum of the num- Since eight readings were taken in all,and 5 roaches were present during each test, the maximum number whichcan be reported for a run is 40.

Table V Total Run No. Sulfoxide Employed Roaches on Chemical Crudesec-oetyl ethyl sulfoxide Methyl n-nonyl suli0xide n-decyl ethylsultoxide.

n-heptyl n-amyl sulfoxide Z-ethylhexyl ethyl sulfoxiden-decyl methylsulfoxide.

n-butyl n-propyl sult'oxlde n-nonyl ethyl sulfoxide Di-n-heptylsulfoxide Dlniethyl sulioxide EXAMPLE VI-STABLE FLY REPELLENCY A numberof the alkyl sulfoxides of the present invention were tested asrepellents for the stable fly, Stomoxys calcitrans (Linn). In thesetests, organdy bags fabricated from a sheet of organdy 10" square sothat one end of the bag is opened, were impregnated with 1 gram of thesulfoxide to be tested dissolved in 6 to 7 milliliters of acetone andwere then suspended on a line to dry. After 24 hours, the bags weredrawn over the hand and exposed to several thousand hungry stable fliesconfined in 30 cubical cages. The flies were reared according to themethod reported by Campau, Baker and Morrison in Journal of EconomicEntomology, 46, 524 (1953). The time to the first bite was recorded, andif no bites were sustained in 5 minutes, the bag Was withdrawn and theprocedure repeated the following day. The period of efiective repellencywas recorded as the number of days from. the day the bags wereimpregnated to the day when '9 the flies bit constantly. Random biteswere not considered to show a loss of effective repellency. The resultsof these tests are expressed below as Table VI.

Table VI Period of Effective Repellency Snlfoxide Tested It will benoted that Table VI includes compounds not falling within the scope ofthe formula of the claims. These are at the end of the table.

The preceding examples clearly demonstrate the superiority of theinsect-combating agents of this invention. For example, the first sixruns of Table I, representing knock-down agents of this invention, aremuch superior to the knock-down agents of the last six runs,representing controls. Similarly, Example II demonstrates theineffectiveness of dimethyl sulfoxide as a pyrethrum synergist, andpoints out the excellent results ob- ,tained with the dialkyl sulfoxidesof this invention.

Again in Example 111, the last two runs, control runs, are greatlyinferior to the preceding runs which represent the knock-down agentswithin the scope of this invention. In Example IV, a comparison of runs1 through 18, representing the invention, with runs 19 through 25,control runs, will again demonstrate the superiority of the sulfoxidesof this invention as housefly repellents. Runs 1 through 23 of Table Vdemonstrate the effectiveness of the sulfoxides of this invention asroach repellents, and it is clearly shown that the compounds following,which are not in the scope of this invention, that is, runs 24 and 25,are ineffective for this purpose. It is also shown by comparing thefirst 21 runs of Table VI, representing the invention, with theremainder of the runs, control runs, that the sulfoxides of thisinvention are excellent repellents for stable flies. One skilled in theart using the above data can readily select the sulfoxide for mosteffective results in a given application.

Generally speaking, the sulfoxides discussed herein have a fairly lowtoxicity. The sulfoxides of this invention were fed to chickens byformulating chicken feed containing one-half percent by weight of one ofthe sulfoxides described herein. There were no noticeable effects on thechickens health or rate of growth after feeding these compositions tothe chickens for periods up to about one month. One of the sulfoxideshaving been noted to have produced irritation of the human skin,the-reader is cautioned to exercise routine precautions in dealing withthese materials. 7

Reasonable variation and modification are possible within'the scopeof'the foregoing disclosure and the appended claims to the invention,the essence of which is that certain selected alkylsulfoxides havebeend-iscov- '10 ered to be excellent insecticides, additives forinsecticidal compositions, said sulfoxides possessing excellentknockdown properties and possessing also a repelling action, asdescribed.

We claim:

1. A method of combating an insect which comprises applying to the placeat which said insect is to be combated a composition containing 0.25 to15 percent by weight of the total composition of a compound having thefollowing structural characteristics:

wherein R is an n-alkyl radical having 1-12 carbon atoms, R is a radicalselected from the group consisting of nand secondary alkyl radicalshaving 1-8 carbon atoms and wherein the total carbon atoms in R and Rare in the range 7-13 inclusive, the said compound being suspended in aninsect-combating adjuvant.

2. A composition for combating insects comprising pyrethrum and 0.25 to5 weight percent based on the total composition, of a compound havingthe following structural characteristics:

wherein R is an n-alkyl radical having 1-12 carbon atoms, R is a radicalselected from the group consisting of nand secondary alkyl radicalshaving 1-8 carbon atoms and wherein the total carbon atoms in R and Rare in the range 7-13 dispersed in an insect-combating adjuvant.

3. A method according to claim 1 wherein the composition contains 1 to 5weight percent of said compound.

4. A method of combating an insect which comprises subjecting saidinsect to an effective quantity of a compound having the followingstructural characteristics 0 R1i9 iR2 wherein R is an n-alkyl radicalhaving l-l2 carbon atoms, R is a radical selected from the groupconsisting of nand secondary alkyl radicals having 1-8 carbon atoms andwherein the total carbon atoms in R and R are in the range 7-13inclusive.

5. A method of combating an insect which comprises subjecting saidinsect to an effective quantity of n-butyl n-propyl sulfoxide.

6. A method for repelling an insect which comprises subjecting saidinsect to an effective amount of a solution or dispersion containing,based upon the weight of the composition, 0.5-10 weight percent of acompound having the following structural characteristics R1- -Rz whereinR is an n-alkyl radical having l-12 carbon atoms, R is a radicalselected from the group consisting of nand secondary alkyl radicalshaving l-8 carbon atoms and wherein the total carbon atoms in R and Rare in the range 7-13 inclusive.

7. A method for combating insects within a confined space whichcomprises applying to said space a compound having the followingstructural characteristics wherein R is an n-alkyl radical having l-l2carbon atoms, R is a radical selected from the group consisting of nandsecondary alkyl radicals having l-8 carbon atoms and wherein the totalcarbon atoms in R and R are in the range 7-13 inclusive.

8. A method of decreasing the amount of pyrethrum required in an insectcombating composition which comprises replacing at least a portion ofthe pyrethrum with a compound selected from the group of compoundshaving the following structural characteristics wherein R is an n-alkylradical having 1-12 carbon atoms, R is a radical selected from the groupconsisting of nand secondary alkyl radicals having 1-8 carbon atoms andwherein the total carbon atoms in R and R are in the range 7-13inclusive by first determining the amount of pyrethrum in said insectcombating composition and then replacing at least a portion thereof witha compound as stated herein.

9. A method of knocking down an insect which comprises applying to saidinsect an effective amount of a knockdown material comprising anappreciable amount of a compound having the following structuralcharacteristics wherein R is an n-alkyl radical having 1-12 carbonatoms, R is a radical selected from the group consisting of nandsecondary alkyl radicals having 1-8 carbon atoms and wherein the totalcarbon atoms in R and R are in the range 7-13 inclusive.

10. A method for repelling flies, such as house flies and stable flies,which comprises applying at the locus from which said flies are to berepelled an effective amount of a solution or dispersion containing,based upon the weight of the composition, 0.5-10 weight percent of acompound having the following structural characteristics II R1SR2 ingstructural characteristics wherein R is an n-alkyl radical having 1-12carbon atoms, R is a radical selected from the group consisting of nandsecondary alkyl radicals having 1-8 carbon atoms and wherein the totalcarbon atoms in R and R are in the range 7-13, inclusive.

12. A method of combatting an insect with comprises subjecting saidinsect to an effective quantity of ethyl n-hexyl sulfoxide.

13. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of di-nbutyl sulfoxide.

14. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of n-heptyl methyl sulfoxide.

15. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of n-amyl n-propyl sulfoxide.

16. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of n-amyl n-butyl sulfoxide.

. 17. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of n-p'ropyl n-hexyl sulfoxide.

18. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of ethyl n-heptyl sulfoxide. I

19. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of methyl n-octyl sulfoxide.

.20. A method of combatting an insect which comprises subjecting saidinsect to an elfecitve quantity of di-namyl sulfoxide.

21. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of n-butyl n-hexyl sulfoxide. I

22. A method of combatting an insect which comprises subjecting saidinsect to an elfective quantity of n-heptyl n-propyl sulfoxide.

23. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of ethyl n-octyl sulfoxide.

24. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of Z-ethylhexyl ethyl sulfoxide.

25. A method of combatting an insect which comprises subjecting'saidinsect to an effective quantity of methyl n-nonyl sulfoxide.

26. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of sec-octyl ethyl (crude) sulfoxide.

27. A method of combatting an insect which comprises subjecting'saidinsect to an elfective quantity of n-butyl n-heptyl sulfoxide.

28. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of n-amyl n-hexyl sulfoxide.

29. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of n-octyl n-propyl sulfoxide.

30. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of n-decyl methyl sulfoxide.

31. A method of combatting an insect which comprises subjecting saidinsect to an elfective quantity of n-nonyl ethyl sulfoxide.

32. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of di-nheXyl sulfoxide.

33. A method of combatting an insect which comprises subjecting saidinsect to an elfective quantity of n-butyl n-octyl sulfoxide.

34. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of n-heptyl n-amyl sulfoxide.

35. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of methyl n-undecyl sulfoxide.

36. A method of combatting an insect which comprises subjecting saidinsect to an efiective quantity of n-decyl ethyl sulfoxide.

37. A method of combatting an insect which comprises subjecting saidinsect to an effective quantity of n-dodecyl methyl sulfoxide.

References Cited in the file of this patent UNITED STATES PATENTSGoodhue et a1. Oct. 6, 1953 OTHER REFERENCES

1. A METHOD OF COMBATING AN INSECT WHICH COMPRISES APPLYING TO THE PLACEAT WHICH SAID INSECT IS TO BE COMBATED A COMPOSITION CONTAINING 0.25 TO15 PERCENT BY WEIGHT OF THE TOTAL COMPOSITION OF A COMPOUND HAVING THEFOLLOWING STRUCTURAL CHARACTERISTICS: